Memory module for platform with non-volatile storage

ABSTRACT

A system that includes a non-volatile memory subsystem having non-volatile memory. The system also includes a plurality of memory modules that are separate from the non-volatile memory subsystem. Each memory module can include a plurality of random access memory packages where each first random access memory package includes a primary data port and a backup data port. Each memory module can include a storage interface circuit coupled to the backup data ports of the random access memory packages. The storage interface circuit offloads data from the memory module in the event of a power loss by receiving data from the backup data ports of the random access memory packages and transmitting the data to the non-volatile memory subsystem.

BACKGROUND

Memory systems can include a number of dynamic random access memory(DRAM) memory devices to store data. DRAM allows for high densitystorage, but DRAM is volatile memory and does not retain its data whenpower is removed.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the embodiments herein can be readily understood byconsidering the following detailed description in conjunction with theaccompanying drawings.

FIG. 1 is schematic illustration of a memory system, according to oneembodiment.

FIG. 2 is a more detailed view of a memory module from FIG. 1, accordingto an embodiment.

FIG. 3 is more detailed view of a DRAM memory package from FIG. 1,according to an embodiment.

FIG. 4 is flowchart illustrating states of operation in the memorysystem, according to an embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

Reference will now be made in detail to several embodiments of thepresent disclosure, examples of which are illustrated in theaccompanying figures. It is noted that wherever practicable similar orlike reference numbers may be used in the figures and may indicatesimilar or like functionality. The figures depict embodiments of thepresent disclosure for purposes of illustration only. One skilled in theart will readily recognize from the following description thatalternative embodiments of the structures and methods illustrated hereinmay be employed without departing from the principles, or benefitstouted, of the disclosure described herein.

FIG. 1 is schematic illustration of a memory system 5, according to oneembodiment. In one embodiment, the memory system 5 represents acomputing device such as a server. The memory system 5 includes amotherboard 60. Two memory modules 20 and a memory controller 30 areconnected to the motherboard 60. The memory modules 20 may be insertedinto memory module sockets of the motherboard 60, and the memorycontroller 30 may be soldered to the motherboard 60 or connected to asocket of the motherboard 60.

The memory system 5 also includes a non-volatile memory (NVM) databackup subsystem 70. In one embodiment, in the event of a power loss,data in the memory modules 20 is backed up by offloading data from thememory modules 20 to the NVM data backup subsystem 70 and storing thedata in the NVM data backup subsystem 70. The data is offloaded byreading data from the DRAM memory packages 10 through backup data ports(not shown in FIG. 1) of the DRAM memory packages 10 and transmittingthe data to the NVM data backup subsystem 70. When power is restored,the backed up data is restored by transferring the backed up data fromthe NVM data backup subsystem 70 to the memory modules 20.

The memory controller 30 and the memory modules 20 are interconnectedvia a data channel 12 and a command and address (C/A) channel 14. Thedata channel 12 includes multiple signal lines for carrying data signals(DQ) and data strobe (DQS) signals in parallel between the memorycontroller 30 and the memory modules 20. The memory controller 30 canread data from and write data to the memory modules 20 via the datachannel 12. In one embodiment, the data channel 12 carries 72 DQ signalsand 8 DQS signals. The C/A channel 14 includes multiple signal lines forcarrying C/A signals such as address signals (ADDR), chip select signals(CS), clock signals (CLK), row address strobe (RAS), column addressstrobe (CAS) as well as other types of control signals from the memorycontroller 30 to the memory modules 20.

The memory controller 30 can also detect whether there will or has beena power loss that affects a power supply voltage of the memory system 5.When this occurs, the memory controller 30 transmits a data save signal16 to the memory modules 20. The data save signal 16 indicates that thedata in the memory modules 20 should be saved. The memory modules 20 mayeach provide the data save signal 16 to the central backup controller 80through the backup link 78. In some embodiments the memory controller 30may provide the data save signal 16 directly to the central backupcontroller 80.

In one embodiment, the memory controller 20 is an integrated circuit(IC) chip that controls the operation of the memory system 10. Examplesof a memory controller 20 include a central processing unit (CPU), agraphics processing unit (GPU), a system on chip (SoC), etc.

Each memory module 20 can include a printed circuit board (PCB) 22 andan edge connector 24 located at the edge of the PCB. The edge connector24 can include multiple conductive pins that form electrical andphysical connections with a socket of the motherboard 60. In oneembodiment, the memory module 20 can be a dual in line memory module(DIMM). Each memory module 20 includes several DRAM memory packages 10.Each DRAM memory package 10 includes one or more integrated circuitsthat store data in DRAM memory cells. The DRAM memory cells are volatileand lose their data when power is removed from the DRAM memory packages10. The DRAM memory packages 10 can include a single DRAM die ormultiple dies of DRAM, for example in a stack configuration.

The memory module 20 also includes a non-volatile storage port interfacecircuit (NVSP) 25. When there is a power loss, the NVSP 25 offloads datafrom the DRAM memory packages 10 by transferring the data to the NVMdata backup subsystem 70 through a corresponding data backup link 78.When power is restored, the NVSP 25 restores the data to the DRAM memorypackages 10 by receiving the data from the NV data backup subsystem 70across the corresponding data backup link 78. The NVSP 25 can be asingle integrated circuit, or can be multiple integrated circuits. TheNVSP 25 can be implemented with an application specific integratedcircuit (ASIC), a programmable logic device (CPLD) or a fieldprogrammable gate array (FPGA). Additional details of the memory module20 and its components will be explained by reference to FIG. 2.

The NVM data backup subsystem 70 includes a central backup controller 80and a NVM storage device 90. The NVM storage device 90 includesre-writable non-volatile memory cells that store data in a non-volatilemanner, and which retain data even when a power supply voltage of theNVM storage device 90 is not present. For example, the non-volatilememory cells can be NAND or NOR based memory cells. The NVM storagedevice 90 can be, for example, a solid state drive (SSD) or a flashmemory chip. In the event of a power loss, the central backup controller80 receives data from the NVSP 25 and writes the data to the NVM storagedevice 90, thereby backing up the data from the memory modules 20. Whenpower is restored, the central backup controller 80 reads the backed updata from the NVM storage device 90 and transfers the backed up data toNVSP 25. The central backup controller 80 can be a single integratedcircuit or a combination or several integrated circuits.

The NVM data backup subsystem 70 serves as centralized NVM storage thatis shared amongst several different memory modules 20. The NVM databackup subsystem 70 is separate from and external to the memory modules20. By separating the NVM data backup subsystem 70 from the memorymodules 20, more DRAM memory packages 10 can be added to a memory module20 to increase the capacity of the memory modules 20 while stillproviding data backup capabilities in the event of a power failure. InFIG. 1, the NVM data backup subsystem 70 is shown to be separate fromthe motherboard 60. In some embodiments, all of or portions of the NVMdata backup subsystem 70 can be integrated with the motherboard 60. TheNVM data backup subsystem 70 can also include a supercapacitor orbattery (not shown) that provides a source of power to the NVM databackup subsystem 70 and memory modules 20 for a short amount of time,even when there is loss of power to the rest of the memory system 5.

FIG. 2 is a more detailed view of a memory module 20 from FIG. 1,according to an embodiment. The memory module 20 in FIG. 2 can representany of the memory modules 20 from FIG. 1. As previously described, thememory module 20 includes DRAM memory packages 10, an edge connector 24and a NVSP 25. In addition, the memory module 20 includes data buffercircuits 202, a registered clock driver (RCD) 210, and a data backupconnector 220.

The memory module 20 includes eighteen DRAM memory packages 10 organizedinto a single 72 bit wide rank of memory controlled by a single chipselect signal. Each DRAM memory package 10 includes a primary x4 dataport A-IO and a backup x4 data port B-IO. The primary data ports A-IOare used for transferring data with the memory controller 30 (via thedata buffers 202, edge connector 24, and primary data channel 12) duringnormal memory access operations. The backup data ports B-IO are used fortransferring data with the NVSP 25 in the event of a power loss, or torestore data that was backed up during a power loss.

Using the backup data ports B-IO for transferring data with the NVSP 25,instead of using the primary data ports A-IO, can reduce the loading onthe primary data ports A-IO. Extra loading can cause signal reflections,distort signal integrity, and reduce maximum IO speed. Using the backupdata ports B-IO for transferring data with the NVSP 25 allows data andbackup and restore capabilities to be added to a memory system 5,without affecting the maximum IO speed of data transferred via theprimary data ports A-IO.

In another embodiment the memory module 20 can include more or less thaneighteen DRAM memory packages 10. In another embodiment, DRAM memorypackages 10 can be organized into more than one memory rank. Forexample, other embodiments can include two or four ranks of memorypackages 10 where each rank is controlled by its own chip select signal.As another example, the DRAM memory packages 10 can be multi-rank memorypackages that receive multiple chip select signals.

Referring briefly to FIG. 3, illustrated is a more detailed view of aDRAM memory package 10 according to an embodiment. The memory package 10includes a primary data port A-IO 304, backup data port B-IO 306, portselection circuit 308, multiplexing circuit 312, DRAM core 314 and aclock synchronization circuit 326. The memory package 10 can includedone or more IC dies, and the components shown in FIG. 3 can be locatedon one or more of the dies.

In one embodiment, the primary data port A-IO 304 is a x4 data port thatcorresponds to four data signals and a data strobe signal. Similarly,the backup data port B-IO 304 is a x4 data port that corresponds to fourdata signals and a data strobe signal. Each data port can represent theexternal connection point between the internal circuits of a DRAM memorypackage 10 and circuits external to the DRAM memory package 10.

The DRAM core 314 includes a large number of DRAM cells organized intobanks, rows and columns. Each DRAM cell can store a bit of data in avolatile manner. Data is written to or read from the DRAM core 314through a data access path 316.

The port selection circuit 308 decodes a control command received viathe secondary control and address bus QA or QB and determines, from thecontrol command, whether the primary data port A-IO 304 or secondarydata port A-IO 306 is selected for data transfer. The port selectioncircuit 308 then generates a port selection signal 310 that has adifferent logic state depending on whether the selected port is port 304or 306.

The multiplexing circuit 312 selectively couples either the primary dataport A-IO 304 or the secondary data port B-IO 306 to the DRAM core 314through a data access path 316. The multiplexing circuitry couples onlyone of the primary data port A-IO 304 or the backup data port A-IO 306to the data access path at a time. The multiplexing circuitry 312selects between the primary data port A-IO 304 and the secondary dataport B-IO 306 under the control of the port selection signal 310. Themultiplexing circuitry 312 can include both a multiplexer circuit toroute data from a selected data port 304 or 306 to the data access path316 during write operations. The multiplexing circuitry 312 can alsoinclude a de-multiplexing circuit to route data from the data accesspath 316 to a selected one of the data ports 304 or 306 during readoperations.

The clock synchronization circuit 326 receives an input clock and thengenerates an output clock that is synchronized to the input clock. Theoutput clock is used to control the timing of a DQS signal and datasignals transmitted by the DRAM memory package 10 via the primary dataport A-IO 304 or secondary data port A-IO 306. Examples of the clocksynchronization circuit 326 include a delay locked loop (DLL) or phaselocked loop (PLL). In one embodiment, the clock synchronization circuitcan be selectively disabled when offloading data from or restoring datato the DRAM memory package 10.

Referring back to FIG. 2, the data buffers 202 are coupled between theDRAM memory packages 10 and the edge connector 24. The data buffers 202buffer data that is being transferred between the DRAM memory packages10 and the edge connector 24. The data buffers 202 reduce the loading onthe primary data channel 12 so that additional memory ranks can beincluded in the memory module 20 without increasing the loading on theprimary data channel 12. Each data buffer 202 can buffer 8 data DQsignals and one data strobe signal DQS (DQS is not shown in FIG. 2).Each of the data buffers 202 can be an IC chip. During write operationsinitiated by the memory controller 30, the data buffers 202 receive datasignals from the memory controller 30 (via the data channel 12 and edgeconnector 24) and provide the data signals to the DRAM memory packages10. During read operations initiated by the memory controller 30, thedata buffers 202 receive data signals from the DRAM memory packages 10and provide the data signals to the memory controller 30 (via the datachannel 12 and edge connector 24). In some embodiments, the memorymodule 20 does not have any data buffers 202 and the primary data portsA-IO are connected directly to the edge connector 24 with signal traces.

The register clock driver RCD 210 is coupled to the edge connector 24,data buffers 202, DRAM memory packages 10, data backup connector 220,and NVSP 25. The registered clock driver RCD 210 receives commands fromthe memory controller 30 (via the C/A channel 14 and edge connector 24).The registered clock driver RCD 210 transmits those commands to thememory devices 10 through the secondary C/A channels QA and QB. Theregistered clock driver RCD 210 can control the operation of the databuffers 202 through the buffer command BCOM channel. The registeredclock driver RCD 210 can also receive commands through the backup C/Achannel 236 in the event of a power loss and control the DRAM memorypackages 10 and data buffers 202 according to those commands. Theregistered clock driver RCD 210 can be an IC chip. In one embodiment,the RCD 210 may be referred to as a C/A buffer circuit.

The data backup connector 220 represents a physical connector that isused to connect the memory module 20 to the data backup link 78. Thedata backup connector 220 can be a ribbon cable connector that has aphysical structure that is configured to connect to an end of a ribboncable. In this situation the backup link 28 represents a ribbon cable.Alternatively, the data backup connector 220 can be integrated into theedge connector 24. In this situation the data backup link 28 representstraces of the motherboard 60.

The data backup link 78 can include several wires that carry differenttypes of signals. The data backup link 78 can includes wires for aserial link 238. In one embodiment, the serial link 238 is a PCI-expresslink, a serial ATA (SATA) link, or another type of communication link.The data backup link 78 can include additional wires for a backup C/Achannel 236. The data backup link 78 can also include an additional wirefor the data save signal 16.

The NVSP 25 provides an interface between the DRAM memory packages 10and the NVM data backup subsystem 70. The NVSP 25 includes aserializer/deserializer circuit 232 and a synchronization circuit 234.The NVSP interface circuit 30 is coupled to the backup data ports B-IOsof the memory devices 10 via the backup data channel 230. The backupdata channel 230 is a multi-bit parallel data channel similar to theprimary data channel 12. The NVSP 25 is also coupled to data backupconnector 220 through the serial link 238 and the backup C/A channel236.

In the event of a power loss, the serializer/deserializer circuit 232receives data from the DRAM memory packages 10 through the backup dataports B-IOs, serializes the data, and then transmits the serialized datato the NVM data backup sub-system 70 via the serial link 238. When poweris restored, the serializer/deserializer circuit 232 receives the backedup data from the NVM data backup sub-system 70 via the serial link 238,deserializes the data, and writes the deserialized data to the DRAMmemory packages 10 through the backup data ports B-IOs.

The synchronization circuit 234 aligns memory access commands on thebackup C/A channel 236 with the data written to the DRAM memory packages10. For example, a known command to data relationship (e.g. DRAM writelatency) may required between the time a memory access command arrivesat the DRAM memory packages 10 and when data can be written to the DRAMmemory packages 10. The synchronization circuit 234 can set the delaywith which data is written to the DRAM memory packages 10 to ensure thatthe relationship is met.

FIG. 4 is flowchart illustrating states of operation in the memorysystem, according to an embodiment. The first state is the normaloperating state 405. During the normal operating state 405, the powersupply voltages in the memory system 5 are at their proper and stablelevels. The registered clock driver RCD 210 receives commands from thememory controller 30 through the primary C/A channel 14, and controlsthe data buffers 202 and DRAM memory packages 10 in accordance withthose commands. The memory controller 30 also writes data to and readsdata from the DRAM memory packages 10 through the primary data channel12. The data buffers 202 are powered on and buffer data between theprimary data ports A-IO of the DRAM memory packages 10 and the memorycontroller 30.

The second state is the power loss state 410. The power loss state 410occurs when the memory controller 30 detects that there has been or willbe a loss of power in the memory system 5. For example, a power loss canbe detected with a power monitoring circuit that monitors the state of apower supply voltage (e.g. 12V, 5V) and compares the power supplyvoltage to a threshold. The power loss can be an un-planned power lossthat is occurring as a result of a hardware failure. When a power lossis detected, the memory controller 30 asserts the memory save signalSAVE_N to indicate that there is a power loss and that the data in theDRAM memory packages 10 needs to be offloaded. The memory save signalSAVE_N 16 is provided to the memory module 20, which then passes thesignal on to the central backup controller 80.

Upon receiving the memory save signal SAVE_N 16, the central backupcontroller 80 sends one or more initial backup commands to the memorymodule 20 across the data backup link 78, such as through the backup C/Achannel 236. In response to these commands, the registered clock driverRCD 210 stops accepting commands from the primary C/A channel 14. Thecommands also cause the DRAM memory packages 10 to disable their primarydata ports A-IOs and to enable their backup data ports B-IOs. Forexample, the commands can cause the multiplexing circuit 312 toselectively connect backup data port 306 to the data access path 316 butto disconnect primary data port 304 from the data access path 316.

The commands can cause the registered clock driver RCD 210 to turn offthe data buffers 202. Turning off the data buffers 202 can involveplacing the data buffers 202 into clock stopped power down mode. Thecommands can also cause the DRAM memory packages 10 to turn off theirinternal clock synchronization circuits 326. Turning off the databuffers 202 and the clock synchronization circuits 326 reduces the powerconsumed by the memory module 20 in the event of a power loss. In oneembodiment, the RCD 210 can turn off the data buffers 202 or turn offthe clock synchronization circuits 326 in response to commands from thememory controller 30.

The central backup controller 80 then sends read commands to the memorymodule 20 across the link 78, such as through the backup C/A channel236. The NVSP 25 of a memory module 20 receives data from the DRAMmemory packages 10 through the backup data ports B-IO, serializes thedata, and transmits the serialized data to the central backup controller80. The central backup controller 80 receives the data through the databackup link 78 and then writes the data into the NVM device 90, therebysaving and backing up the data.

The central backup controller 80 can retrieve data concurrently from allof the memory modules 20 at once. Alternatively, data can be retrievedfrom one memory module 20 before data is retrieved from the next memorymodule 20.

The third state is the power restored state 415. The power restoredstate 415 begins when the central backup controller 80 detects thatpower has been restored to the memory system 5. Once power has beenrestored, the central backup controller 80 reads the backed up data fromthe NVM device 90 and sends the backed up data to the appropriate memorymodule 20 (via the serial link 238 of the data backup link 78), andsends one or more memory write commands to the memory module 20 (via thebackup C/A channel 236 of the data backup link 78). The NVSP interfacecircuit 30 receives the backed up data and transmits the data to theDRAM memory packages 10 through the backup data ports B-IO. As a result,the data in the DRAM memory packages 10 is fully restored to its statebefore power was lost. This process can be repeated for each memorymodule 20 until all the backed up data and restored to all of the memorymodules 20. The data buffers 202 and the clock synchronization circuits326 can also be turned off when restoring data to reduce powerconsumption.

In one embodiment, a system comprise a NVM data backup subsystemincluding non-volatile memory. The system also comprises a plurality ofmemory modules that are separate from the NVM data backup subsystem. Atleast one memory module comprises a plurality of random access memorypackages. Each random access memory package including a primary dataport and a backup data port. The memory module also comprises a storageinterface circuit coupled to the backup data ports of the random accessmemory packages. The storage interface circuit offloads data from thememory module in the event of a power loss by receiving data from thebackup data ports of the random access memory packages and transmittingthe data to the non-volatile memory subsystem that is external to andseparate from the memory module.

In one embodiment, a representation of components described herein maybe stored as data in a non-transitory computer-readable medium (e.g.hard disk drive, flash drive, optical drive). These representations mayin the form of, for example, behavioral level descriptions, registertransfer level descriptions, logic component level descriptions,transistor level descriptions or layout geometry-level descriptions.

Upon reading this disclosure, those of skill in the art may appreciatestill additional alternative designs for data backup in a memory system.Thus, while particular embodiments and applications of the presentdisclosure have been illustrated and described, it is to be understoodthat the disclosure is not limited to the precise construction andcomponents disclosed herein. Various modifications, changes andvariations which may be apparent to those skilled in the art may be madein the arrangement, operation and details of the method and apparatus ofthe present disclosure herein without departing from the spirit andscope of the disclosure as defined in the appended claims.

What is claimed is:
 1. A system comprising: a non-volatile memory (NVM)data backup subsystem including non-volatile memory; and a plurality ofmemory modules that are separate from the NVM data backup subsystem,wherein a first memory module of the memory modules comprises: aplurality of first random access memory packages, each first randomaccess memory package including a primary data port and a backup dataport; and a first storage interface circuit coupled to the backup dataports of the first random access memory packages, the first storageinterface circuit offloading data from the first memory module in theevent of a power loss by receiving data from the backup data ports ofthe first random access memory packages and transmitting the data to theNVM data backup subsystem.
 2. The system of claim 1, wherein the firstmemory module comprises: a data backup connector; wherein the firststorage interface circuit transmits the data to the NVM data backupsubsystem via the data backup connector.
 3. The system of claim 2,wherein the data backup connector is a cable connector.
 4. The system ofclaim 2, wherein the data backup connector is a dual in line memorymodule edge connector.
 5. The system of claim 1, wherein the firstmemory module comprises: an edge connector at an edge of the firstmemory module; and a plurality of data buffer circuits to buffer databetween the edge connector and the primary data ports of the firstrandom access memory packages, wherein the data buffer circuits areturned off while the storage interface circuit is offloading data. 6.The system of claim 1, wherein clock synchronization circuits in thefirst random access memory packages are turned off while the storageinterface circuit is offloading data.
 7. The system of claim 1, whereinthe first storage interface circuit comprises a serializer circuit toserialize the data received from the backup data ports of the firstrandom access memory packages into serialized data, wherein the data istransmitted to the NVM data backup subsystem is the serialized data. 8.The system of claim 1, wherein each first random access memory packagecomprises: a random access memory core; and multiplexing circuitry thatis coupled to the random access memory core through a data access path,the multiplexing circuitry selectively coupling one of the primary dataport and the backup data port to the data access path at a time.
 9. Thesystem of claim 1, wherein the first storage interface circuit restoresthe data to the first memory module when power is restored by receivingthe data from the NVM data backup subsystem and writing the data to thebackup data ports of the random access memory packages.
 10. The systemof claim 1, wherein a second memory module of the memory modulescomprises: a plurality of second random access memory packages, eachsecond random access memory package including a primary data port and abackup data port; and a second storage interface circuit coupled to thebackup data ports of the second random access memory packages, thesecond storage interface circuit offloading data from the second memorymodule in event of the power loss by receiving data from the backup dataports of the second random access memory packages and transmitting thedata to the NVM data backup subsystem.
 11. The system of claim 10,wherein the non-volatile memory subsystem comprises: a non-volatilememory device that includes the non-volatile memory; and a centralbackup controller to receive the data from the first memory module andto receive the data from the second memory module, the central backupcontroller writing the data from the first memory module and the datafrom the second memory module to the non-volatile memory device.
 12. Amemory module comprising: a plurality of random access memory packages,each including a primary data port and a backup data port; and a storageinterface circuit coupled to the backup data ports of the random accessmemory packages, the storage interface circuit to offload data from thememory module in the event of a power loss by receiving data from thebackup data ports of the memory packages and transmitting the data to anexternal non-volatile memory (NVM) data backup subsystem that isseparate from the memory module.
 13. The memory module of claim 12,wherein the memory module comprises: a data backup connector; whereinthe storage interface circuit transmits the data to the external NVMdata backup subsystem via the data backup connector.
 14. The memorymodule of claim 13, wherein the data backup connector is a ribbon cableconnector.
 15. The memory module of claim 13, wherein the data backupconnector is a dual in line memory module edge connector.
 16. The memorymodule of claim 12, further comprising: an edge connector at an edge ofthe memory module; and a plurality of data buffer circuits to bufferdata between the edge connector and the primary data ports of the randomaccess memory packages, wherein the data buffer circuits are turned offwhile the storage interface circuit is offloading data.
 17. The memorymodule of claim 12, wherein a clock synchronization circuit in therandom access memory packages is turned off while the storage interfacecircuit is offloading data.
 18. The memory module of claim 12, whereinthe storage interface circuit comprises a serializer circuit toserialize the data received from the backup data ports of the randomaccess memory packages into serialized data, wherein the data istransmitted to the external NVM data backup subsystem is the serializeddata.
 19. The memory module of claim 12, wherein each random accessmemory package comprises: a random access memory core; and multiplexingcircuitry that is coupled to the random access memory core through adata access path, the multiplexing circuitry selectively coupling one ofthe primary data port and the backup data port to the data access pathat a time.
 20. The memory module of claim 12, wherein the storageinterface circuit restores the data to the memory module when power isrestored by receiving the data from the external NVM data backupsubsystem and writing the data to the backup data ports of the randomaccess memory packages.